The advantages of on-site electrolzers for the production of sodium hypochlorite from either synthetic or natural brines are obvious. For example, it is well known that modern sewage and water treatment facilities demand large quantities of chlorine as a biocidal agent. Chlorine, in the form of a gas or anhydrous liquid, poses hazardous risks in handling and storage. Even in the form of sodium hypochlorite, which is relatively safe to use, very large shipments of dilute solutions to the site of intended use present problems of storage and logistics.
Prior art electrolyzers of high electrical and salt efficiencies are generally complex and costly to manufacture and service. All present day electrolyzers employ anodes that wear out, i.e., they lose their catalytic coating and must frequently be completely disassembled and rebuilt. Furthermore, profuse numbers of connections often incorporated in the more sophisticated designs are potential sources of leaks of corrosive electrolyte which can be destructive, and of hydrogen which may collect in hazardous concentrations.
Power consumption is adversely affected by hydrogen gas accumulation in electrolyzers, leading to various add-on devices for separating the hydrogen from the electrolyte which contribute to additional system complexity.
Some available electrolyzers are very sensitive to scale buildup on electrodes due to the impurities in brines such as sea water. Acid cleanings may be necessary on a frequent basis further adding to maintenance cost.
It has been established by reliable investigations, and through experience, that low brine temperatures, typically 34.degree. to 50.degree. F., contribute to reduced anode coating life. High current densities also reduce the life of the precious coatings employed. Conventional electrolyzers are prone to undue reductions in anode life due to variations in conditions that are encountered when used over a wide range of services and geographic locations.
The present invention substantially overcomes the problems abovementioned while providing many related advantages and benefits. The electrolyzer comprises a plurality of electrolytic cells on a chassis inside a cylindrical casing resulting in a modular assembly which may be hydraulically serially connected with other duplicate modules wherein the entire cell structure of any electrolyzer may be easily and rapidly removed for repair thereof, or replaced with reconditioned or new parts preassembled outside the casings with minimal risk of assembly error.
The electrolyzers of the present invention are characterized by improved electrolyte flow paths and electrode plate configurations to resist scaling caused by brine contaminants. The electrolyzers are provided with improved means for removing gaseous products formed in the process of electrolyzing the brine solutions, possess unique and improved dilution water distribution means for extending anode life when electrolyzing synthetic brines and include an electrical conductor arrangement which is simple and yet provides substantially balanced power flow against changes in electrical resistance resulting from changes in electrolyte temperature and salinity to further extend anode life.